Apparatus and method for actuation of injection molding shooting pots

ABSTRACT

Apparatus and method whereby coinjection molding shooting pot actuation structure is configured to be installed in a coinjection hot runner with a coinjection nozzle, the coinjection nozzle having at least two melt channels ending at the same gate. The shooting pot is preferably disposed in one of a mold cavity half and a mold core half. A shooting pot piston is configured to discharge a melt from the shooting pot. A transmission structure is configured to (i) extend through one of the mold cavity half and the mold core half, and (ii) to transmit a force to the shooting pot piston. Actuation structure is disposed on the opposite side of the mold cavity half from the coinjection hot runner, and is configured to provide the force to the transmission structure. This configuration conserves space in the mold.

This application is a divisional of U.S. patent application Ser. No.10/879,575, filed Jun. 30, 2004, the contents of which is incorporatedherein by reference. BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improved coinjection hot runnershooting pot actuation device configured to optimize the space requiredin the mold structure in order to maintain cavity pitch spacing whencompared with similar molds not containing hot runner shooting pots.

2. Description of Related Art

Coinjection molding is typically used to mold multi-layered plasticpackaging articles having a laminated wall structure. Each layer istypically passed through a different annular or circular passageway in asingle nozzle structure and each layer is partially, sequentially,injected through the same gate. Some coinjection hot runner systemsinclude shooting pots to meter material of one plastic resin so thateach cavity of a multi-cavity mold receives an accurate dose of thatresin in the molding cycle. Such systems may also use shooting pots toexert supplementary pressure on the melt during the molding process.

U.S. Pat. No. 4,080,147 to Dumortier discloses a multi-cavity moldemploying a hot runner having a shooting pot associated with eachnozzle/cavity combination. The shooting pot is charged while the mold isopen (FIG. 5), the action causes the hot runner assembly to move awayfrom the manifold backing plate a distance “b”. The mold is closed inFIG. 6, the action causes a valve to block the melt channel to preventbackflow of the resin toward the feeding unit. Then the distance “b” isclosed up by the continuing motion of the machine clamp that causes theresin in the shooting pot to be injected into the mold cavity partiallyfilling it.

WO 02/058908 A1 to Clarke discloses a multi-cavity mold employing a hotrunner having shooting pots. The shooting pots are charged while themold is open without any corresponding movement of the hot runner orcavity plate assembly of the mold. The shooting pots are discharged bythe action of closing the mold by the machine clamp, the resin beingdischarged to completely fill the cavities as the cavity itself closes.The shooting pot piston extends from the cavity side of the mold and isdirectly acted on by the core plate of the mold during closing. Valvesincluded in the hot runner ensure backflow of the resin toward thefeeding unit is prevented during injection.

U.S. Pat. No. 6,152,721 to Schad discloses a shooting pot actuationdevice that comprises a movable plate mounted behind the stationaryplaten of the machine having actuation rods extending through the platento act on the shooting pot pistons mounted in the hot runner of themold. The hot runner assembly is also mounted to the stationary platenof the mold so the shooting pot piston actuators never separate contactwith their corresponding rod actuators mounted on the movable plate.

U.S. Pat. No. 4,966,545 to Brown discloses a shooting pot piston movedin two discrete motions in order to deliver two metered amounts of resinto the same mold cavity from the same shooting pot. The piston isactuated by tandem mounted cylinders in the mold plate and valves areused to prevent backflow to the feeding unit during injection.

U.S. Pat. No. Re. 35,256 to von Buren discloses a clamping piston actingperpendicular to the injection unit's axis to intermittently effect asealing connection to the hot runner system of the mold. The connectionis released and sealed during each molding cycle.

U.S. Pat. No. 5,044,927 to DiSimone discloses a latching mechanism forclamping the injection unit's nozzle to the bushing at the end of spruebar of a stack mold in order to alleviate unequal clamping. Theconnection is released and sealed during each molding cycle.

U.S. Pat. No. 4,207,051 to Wright and U.S. Pat. No. 5,910,327 to Schadboth disclose a stack mold having a telescoping sprue bar that adjustsits length as the mold opens and closes. However the sprue bar'sconnection with the injection unit's nozzle is released and sealedduring each molding cycle.

U.S. Pat. No. 6,413,076 to Dray discloses a machine nozzle thatcontinuously engages the mold's sprue bushing throughout the moldingcycle. An extension from the nozzle remains within a corresponding boreextending from the sprue bushing allowing relative axial movementbetween the two without separation. The channel through the extensionand sprue is open only when the injection unit is advanced toward themold and consequently relative movement between the two causes a valvingaction. See also:

U.S. patent application Ser. No. 10/______ entitled INJECTION MOLDINGMACHINE SHOOTING POT WITH INTEGRAL CHECK VALVE (attorney docket number213201.00214; H-778);

U.S. patent application Ser. No. 10/______ entitled INJECTION MOLDINGMACHINE SPIGOTTED SHOOTING POT PISTON (attorney docket number213201.00213; H-784);

U.S. patent application Ser. No. 10/879,576 entitled INJECTION MOLDINGMACHINE SHOOTING POT WITH INTEGRAL CHECK VALVE;

U.S. patent application Ser. No. 10/879,581 entitled INJECTION MOLDINGMACHINE SPIGOTTED SHOOTING POT PISTON;

U.S. patent application Ser. No. 10/879,621 entitled APPARATUS ANDMETHOD FOR SEALING INJECTION UNIT AND SPRUE;

U.S. patent application Ser. No. 10/879,582 entitled CONTROL SYSTEM FORA DYNAMIC FEED COINJECTION PROCESS;

U.S. patent application Ser. No. 10/880,494 entitled HOT RUNNERCOINJECTION NOZZLE WITH THERMALLY SEPARATED MELT CHANNELS;

U.S. patent application Ser. No. 10/880,493 entitled COINJECTION MOLDINGCOOLED SHOOTING POT; and

U.S. patent application Ser. No. 10/887,353 entitled APPARATUS ANDMETHOD FOR INJECTION MOLDING SHOOTING POT WEDGE FEATURE.

Thus, what is needed is an injection molding shooting pot structurewhich is reliable, easy to assemble, easy to maintain, and whichconserves space in the mold, especially for coinjection molding machineshaving plural mold cavities.

SUMMARY OF THE INVENTION

It is an advantage of the present invention to overcome the problems ofthe related art and to provide an injection molding machine hot runnersystem that is reliable, easy to assemble, easy to maintain, and whichconserves space in the mold, especially for coinjection molding machineshaving plural mold cavities.

According to a first aspect of the present invention, a novelcombination of structure and/or steps are provided for a coinjectionmolding shooting pot actuation structure that is configured to beinstalled in a coinjection hot runner with a coinjection nozzle, thecoinjection nozzle having at least two melt channels ending at the samegate. The shooting pot is preferably disposed in one of a mold cavityhalf and a mold core half. A shooting pot piston is configured todischarge a melt from the shooting pot. A transmission structure isconfigured to (i) extend through one of the mold cavity half and themold core half, and (ii) to transmit a force to the shooting pot piston.Actuation structure is disposed on the opposite side of the mold cavityhalf from the coinjection hot runner, and is configured to provide theforce to the transmission structure. This configuration conserves spacein the mold.

According to a second aspect of the present invention, a uniquecombination of structure and/or steps are provided for an injectionmolding shooting pot actuation apparatus configured to be installed in acoinjection hot runner with a coinjection nozzle, the coinjection nozzlehaving a longitudinal axis and at least two melt channels ending at thesame gate, wherein the shooting pot is disposed in one of a mold cavityhalf and a mold core half. A shooting pot is coupled to at least one ofthe mold cavity half and the mold core half, and is configured todischarge melt to the coinjection hot runner. A shooting pot piston isconfigured to cause the melt in the shooting pot to be discharged to thecoinjection hot runner. A moving member is configured to move theshooting pot piston to cause the melt in the shooting pot to bedischarged to the coinjection hot runner, and actuation structure isconfigured to move the moving member. The moving member and theactuation structure are disposed on an opposite side of the mold cavityhalf from the coinjection hot runner.

According to a third aspect of the present invention, a uniquecombination of structure and/or steps are provided for an injectionmolding shooting pot actuation apparatus configured to be installed in acoinjection hot runner with a coinjection nozzle, the coinjection nozzlehaving at least two melt channels ending at the same gate, wherein theshooting pot is disposed in one of a mold cavity half and a mold corehalf. A shooting pot is configured to be disposed in a mold plate whichmoves with respect to a stationary plate, and a shooting pot piston isconfigured to discharge the shooting pot. Shooting pot piston actuationstructure is configured to move the shooting pot piston from a side ofthe mold plate that is opposite the side which contacts the stationaryplate.

According to a fourth aspect of the present invention, a uniquecombination of steps are provided for method of activating a shootingpot in an injection molding shooting pot actuation apparatus that isconfigured to be installed in a coinjection hot runner with acoinjection nozzle, the coinjection nozzle having at least two meltchannels ending at the same gate, wherein the shooting pot is disposedin one of a mold cavity half and a mold core half. The method includesthe steps of: (i) charging a shooting pot with melt when the mold corehalf and the mold cavity half are closed, the shooting pot beingdisposed in at least one of the mold core half and the mold cavity half;and (ii) using a shooting pot piston actuation structure that extendsthrough at least one of the mold core half and the mold cavity half tocause a shooting pot piston to discharge the melt from the shooting pot.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the presently preferred features of the presentinvention will now be described with reference to the accompanyingdrawings.

FIG. 1 is a schematic section view of a coinjection hot runner mold atthe beginning of a molding cycle with both shooting pots charged and themold closed.

FIG. 2 is a schematic section view of the FIG. 1 embodiment showing thenext stage of the molding cycle in which the clamp activates one of theshooting pots to inject the “A” resin into the mold.

FIG. 3 is a schematic section view of the FIG. 1 embodiment showing thenext stage of the molding cycle in which the plate behind the movingplaten activates the other of the shooting pots to inject the “C” resininto the mold.

FIG. 4 is a schematic section view of the FIG. 1 embodiment showing thenext stage of the molding cycle in which the valve gate is closed andthe molded part is cooling.

FIG. 5 is a schematic section view of the FIG. 1 embodiment showing thenext stage of the molding cycle in which the “A” injector unit chargesthe “A” shooting pot.

FIG. 6 is a schematic section view of the FIG. 1 embodiment showing thenext stage of the molding cycle in which the “C” injector unit chargesthe “C” shooting pot.

FIG. 7 is a schematic section view of the FIG. 1 embodiment showing thenext stage of the molding cycle in which the mold is in open positionand the part is being ejected.

FIG. 8 is a schematic section view of an alternate embodiment in whichboth injection units are mounted in parallel and the “C” actuation meansis incorporated within the mold.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS 1.Introduction

The present invention will now be described with respect to severalembodiments in which a plastic resin coinjection molding machine injects“A” and “C” resins through a coinjection nozzle into a mold cavity.However, the present invention will find applicability in single plasticmolding machines, and/or molding machines which mold other melts such asmetal, composites, etc.

2. The Structure of the Preferred Embodiment

FIGS. 1-7 are schematic section views of a coinjection hot runner mold,showing various parts of the machine at various stages during a moldingcycle which produces a molded part having multilayered walls. The moldincludes a core block 10, and a cavity block 11 that together form amold cavity 12. A coinjection hot runner nozzle 13 includes a first meltchannel 14 (for conveying a plastic resin “A”) and second melt channel15 (for conveying a different plastic resin “C”). The nozzle 13 ismaintained at operating temperature by a heater 16, and is located inthe cavity block 11 by a locating insulator 17. The nozzle 13 ispreferably urged into sealing contact with a first hot runner manifold30 and a second hot runner manifold 40 by spring pack 18. The nozzle 13also contains a valve stem 19 that is actuated by piston 20 in cylinder21 to open and close gate 22 that connects melt channels 14 and 15 tomold cavity 12. See U.S. patent application Ser. No. 10/879,576 entitledINJECTION MOLDING MACHINE SHOOTING POT WITH INTEGRAL CHECK VALVE(attorney docket number 213201.00214; H-778).

The mold has two hot runner manifolds. The first hot runner manifold 30handles the resin “A” and is maintained at optimum operating temperaturefor the resin “A” by first heaters 31. Attached to the manifold 30 is afirst sprue bushing 32 that conveys the resin “A” from a first injectionunit 33. Also attached to the manifold 30 is a first shooting pot 34that contains a first shooting pot piston 35. The second hot runnermanifold 40 handles the resin “C” and is maintained at optimum operatingtemperature for the resin “C” by second heaters 41. Attached to themanifold 40 is a second sprue bushing 42 that conveys the resin “C” froma second injection unit 43. Also attached to manifold 40 is a secondshooting pot 44 that contains a second shooting pot piston 45. As anexample, the distance between the second shooting pot 44 and the nozzle13 may be 60,0 mm.

The second manifold 40 is preferably spaced away from the first manifold30, urged by a compensation element 46. Both of the manifolds 30 and 40are preferably located in a manifold plate 50 that is bolted to thecavity block 11 by fastening means (not shown). Both of the manifolds 30and 40 seal against the nozzle 13 such that their respective meltchannels align and seal with their counterpart melt channels in thenozzle 13 to convey the resins “A” and “C”, respectively, from theshooting pots 34 and 44 to the mold cavity 12 when a valve stem 19 isopen and the respective shooting pot pistons are actuated.

The manifold plate 50 is located and guided on guide pins 51 mounted ina manifold backing plate 52 that is fastened to a machine stationaryplaten 53. When the first injection unit 33 charges the first shootingpot 34 with the resin “A”, the entry of the resin into the shooting potdisplaces the manifold/cavity block assembly away from the manifoldbacking plate 52 a distance of “b”, as shown in FIG. 1. The actuation ofa machine clamp piston 60 via a column 67 that is attached to a movingplaten 63 causes the mold assembly to move towards the stationary platen53, thereby closing or taking up the distance “b”, thus causing thefirst shooting pot piston 35 to inject the resin “A” from the firstshooting pot 34 into the nozzle housing melt channel 14, and therebyinto the mold cavity 12. A ball check valve 36 in a feed channel 37prevents backflow of the injected resin back into the first injectionunit 33. The first injection unit 33 is maintained in sealing contactwith the sprue bushing 32 during these movements of the manifolds 30 and40 and the cavity block 11 by means of a cylinder 54 that is connectedto the first injection unit 33 and a piston 55 that is connected to thestationary platen 53.

The second shooting pot piston 45 is actuated by a rod (or othertransmission structure) 61 that is connected to a plate 62 that ismounted behind the moving platen 63, or alternatively within the moldcore half structure as shown in FIG. 8, and is moved by cylinder meansor other actuation structure 72. Of course, in a multi-cavity mold, theactuation structure 72 may move more than one of the rods 61. The rod61. is preferably co-axial with the second shooting pot piston 45, andparallel to a longitudinal axis of the nozzle 13. When the secondinjection unit 43 charges the second shooting pot 44 with the resin “C”,the entry of the resin into the shooting pot displaces the secondshooting pot piston 45, the rod 61, and the plate 62 away from thesecond manifold 40. The forward movement of the plate 62 causes the rod61 to advance the second shooting pot piston 45 and discharge the resin“C” from the second shooting pot 44 via the channel 64 in the secondmanifold 40, the channel 15 in the nozzle 13, and into the mold cavity12 via the open gate 22. The second ball check valve 65 in the feedchannel 66 prevents backflow of the injected resin into the secondinjection unit 43. The second injection unit 43 is mounted atop the moldassembly and travels with the movable section of the mold, therebymaintaining its sealing contact with sprue 42 throughout the moldingcycle, or alternatively is mounted alongside the first injection unit 33and is connected via a hole in the stationary platen directly to a sprueextension attached to the second manifold as shown in FIG. 8.

3. The Process of the Preferred Embodiment

In operation, the molding cycle starts with the configuration shown inFIG. 1, that is, both of the shooting pots 34 and 44 are charged withtheir respective resins, the valve gate 19 is closed and, the mold isclosed. FIG. 2 shows the next step in the molding cycle. The valve gate19 has been opened by the piston 20, the machine clamp piston 60 hasbeen actuated to move column 67, which in turn moves the moving platen63, the mold core block 10, the mold cavity block 11, and the manifoldassemblies 30 and 40 toward the stationary platen 53 until distance “b”has been taken up. This action displaces the first shooting pot piston35 that injects the resin “A” in the first shooting pot 34 into the moldcavity 12 via the channel 74 in the first manifold 30 and the first meltchannel 14 in the nozzle 13. This metered first shot of resin “A” atleast partially fills the mold cavity 12.

FIG. 3 shows the next step in the molding cycle. The plate 62 isactuated to push the rod 61 against the second shooting pot piston 45that injects the resin “C” inside the second shooting pot 44 into themold cavity 12 via the channel 64 in the second manifold 40 and thesecond melt channel 15 in the nozzle 13. This metered second shot ofresin “C” flows within the earlier metered shot of resin “A” pushing itfurther along the cavity and setting up a multilayered wall in the partin known fashion. The combined amounts of resin injected so farpreferably only partially fill the mold cavity 12.

FIG. 4 shows the next step in the molding cycle. The first injectionunit 33 injects a third shot of resin “A” directly through the meltchannel 37 in the sprue, the channel 74 in the first manifold 30 and thefirst melt channel 14 in the nozzle 13 to fill and pack the mold cavity12. After a brief interval of holding pressure, valve stem 19 is closedby piston 20 and the molded part is allowed to cool.

FIG. 5 shows the next step in the molding cycle. During the cooling ofthe part, the first shooting pot 34 is recharged with resin “A” by thefirst injector 33, feeding resin through the feed melt channel 37.Because the valve stem 19 is in the closed position, the incoming resin“A” can only flow into the first shooting pot 34, thereby displacing thefirst shooting pot piston 35 that in turn pushes the movable moldportion (comprising the core block 10, the cavity block 11, themanifolds 30 and 40, and the manifold plate 50) away from the manifoldbacking plate 52, thus creating the space “b” between them.

FIG. 6 shows the next step in the molding cycle. During the continuedcooling of the part, the second shooting pot 44 is recharged with theresin “C” by the second injector 43, feeding resin through the feedchannel 66. Because valve stem 19 is in the closed position, theincoming resin “C” can only flow into the second shooting pot 44,thereby displacing the second shooting pot piston 45, that in turnpushes back the rod 61 and the plate 62. This recharging activity cantake place simultaneously with the recharging of the “A” resin in thefirst shooting pot 34, since both of the manifolds 30 and 40 (and theirrespective injection units 33 and 43, respectively) can be operatedindependently. After the second shooting pot 44 is recharged, the plate62 is activated by actuator 72 to continue to retract the rod 61 so thatits distal end clears the cavity block 11 as shown in FIG. 6. This is toensure that the rod 61 is not exposed above the mold parting line whenthe mold is opened, as shown in FIG. 7.

FIG. 7 shows the next step in the molding cycle. The part has cooledsufficiently to be ejected so the mold is opened and the part 70 isejected off the core block 10 in a conventional manner. Note that therod 61 has been retracted to clear the parting line so that a robot mayenter between the open mold halves to pick up the ejected part, ifnecessary. Both of the shooting pots 34 and 44 have been re-charged inthe previous step and are ready for injection when the mold closes inthe next step, which is the first step of the next molding cycle. As anexample, the entire molding cycle may take about 12 seconds.

4. Conclusion

Advantageous features according to the present invention include:

-   -   A shooting pot piston actuated by structure that operates from a        side of the mold opposed to that in which the shooting pot        piston is mounted, and such structure is actuated after the mold        has been closed.    -   A shooting pot actuation structure that requires no additional        space within the mold that would cause the spacing between        adjacent mold cavities to be increased or the outer dimensions        of the mold to be increased when compared to a mold for the same        part, and compared to cavitation that does not include a        shooting pot. For example a 96-cavity coinjection mold may have        the same width and breadth (mold area on the platen) as a 96        cavity monolayer mold for the same size perform.

Thus, what has been described is apparatus and process for an injectionmolding shooting pot structure that is reliable, easy to assemble, easyto maintain, and which conserves space in the mold, especially forcoinjection molding machines having plural mold cavities.

The individual components shown in outline or designated by blocks inthe attached Drawings are all well-known in the injection molding arts,and their specific construction and operation are not critical to theoperation or best mode for carrying out the invention.

While the present invention has been described with respect to what ispresently considered to be the preferred embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments. To the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass all suchmodifications and equivalent structures and functions.

All U.S. and foreign patents and patent applications discussed above arehereby incorporated by reference into the Detailed Description of thePreferred Embodiments.

1. A method of activating a shooting pot in an injection moldingshooting pot actuation apparatus configured to be installed in acoinjection hot runner with a coinjection nozzle, the coinjection nozzlehaving at least two melt channels ending at the same gate, wherein theshooting pot is disposed in one of a mold cavity half and a mold corehalf, comprising the steps of: charging a shooting pot with melt whenthe mold core half and the mold cavity half are closed, the shooting potbeing disposed in at least one of the mold core half and the mold cavityhalf; using a shooting pot piston actuation structure that extendsthrough at least one of the mold core half and the mold cavity half tocause a shooting pot piston to discharge the melt from the shooting potto the coinjection hot runner; charging a second shooting pot with asecond melt, the second shooting pot being disposed in the opposite oneof the mold core half and the mold cavity half from said shooting pot;using movement of a moving platen with respect to a stationary platen tocause a second shooting pot piston actuation structure to cause thesecond shooting pot piston to discharge the second melt from the secondshooting pot to the coinjection hot runner.
 2. A method according toclaim 1, wherein said shooting pot piston actuation structure isconfigured to provide the force after the mold cavity half and the moldcore half have closed.
 3. A method according to claim 1, wherein saidshooting pot is disposed in the mold cavity half adjacent andsubstantially parallel to the coinjection nozzle, and wherein saidshooting pot piston actuation structure comprises a rod extendingthrough the mold core half and into the mold cavity half.
 4. A methodaccording to claim 3, wherein said shooting pot piston actuationstructure comprises a cylinder configured to actuate said rod.
 5. Amethod according to claim 3, wherein said rod is configured so as to notproject from a side of the mold core half which faces the mold cavityhalf, when the mold core half and the mold cavity half are fully opened.6. A method according to claim 1, wherein said method is performed in acoinjection plastic injection mold.
 7. A method according to claim 6,wherein the coinjection plastic injection mold has a plurality of moldcavities, and wherein each cavity has at least one said shooting potpiston and at least one transmission structure.
 8. A method according toclaim 1, wherein said shooting pot piston and said shooting pot pistonactuation structure are disposed co-axially and substantially parallelto a longitudinal axis of the coinjection nozzle.
 9. A method accordingto claim 1, wherein the mold cavity half includes the coinjection hotrunner.
 10. A method of coinjection molding first and second melts in aninjection molding shooting pot actuation apparatus configured to beinstalled in a coinjection hot runner with a coinjection nozzle, thecoinjection nozzle having at least two melt channels ending at the samegate, wherein the shooting pot is disposed in one of a mold cavity halfand a mold core half, comprising the steps of: closing the mold coreplate and the mold cavity plate; charging a first shooting pot with thefirst resin and a second shooting pot with the second resin when themold core plate and the mold cavity plate are closed, the first shootingpot being disposed in a manifold plate coupled to the mold cavity plate,the second shooting pot being disposed in the mold cavity plate adjacenta coinjection nozzle; opening a valve gate in the coinjection nozzle,and moving the closed mold core and cavity plates toward the stationaryplate causing a first shooting pot piston coupled to the stationaryplate to discharge the first resin from the first shooting pot through afirst coinjection hot runner and the coinjection nozzle into a moldcavity between the mold core plate and the mold cavity plate; while themold core and cavity plates are closed with the stationary plate,driving a rod from the side of the mold core plate which is opposite theside in contact with the mold cavity plate to cause a second shootingpot piston to discharge the second resin from the second shooting potthrough a second coinjection hot runner and the coinjection nozzle intothe mold cavity; closing the coinjection nozzle valve gate; cooling themelt in the mold cavity to form a molded article; recharging the firstshooting pot with the first resin from a first injector unit, causingthe closed mold core and cavity plates to move away from the stationaryplate; recharging the second shooting pot with the second resin causingthe second shooting pot piston and the rod to move away from the firstand second coinjection hot runners; moving the rod in the direction awayfrom the coinjection hot runners until a distal end of the rod is freefrom the mold cavity plate; and opening the mold core plate and the moldcavity plate to eject the molded article.